460 THE DEPTHS OF THE SEA. [cHAP. 1x. 
while one family type, the Hehinothuride, has been 
hitherto only known in a fossil state, the entire 
group find nearer allies in the extinct faunze of the 
chalk or of the earlier tertiaries than in that of 
the present period. 
As I have already said, the mollusca procured 
during the three years’ dredging are in the hands 
of Mr. Gwyn Jeffreys for identification and descrip- 
tion. From the large number of new species, and 
from the complicated relations which many of the 
forms from deep water bear to species now widely 
separated from them in space, or belonging to past 
geological periods, the task will be a difficult one, 
and we cannot expect its completion for some time 
to come. In the meanwhile, Mr. Gwyn Jeffreys 
has published several preliminary sketches which 
are full of promise that his complete results will 
be of the highest interest. 
Mr. Gwyn Jeffrevs believes that the deep-water 
mollusea which were dredged throughout the whole of 
the area examined from the Ieroe Islands to the coast 
of Spain, are almost all of northern origin. Most of 
the species which have been already described were 
previously known from the Scandinavian seas, and 
many of the undescribed species belong to northern 
genera. He points out that the molluscan fauna 
of the Arctic Sea is as yet almost unknown ; but he 
reasons from the large collections made at Spitz- 
bergen by Professor Torell, and from the fact that 
fragments of mollusca have been brought up in 
many deep-sea soundings within the Arctic circle, 
that the fauna is probably varied and rich. He 
instances soundings taken in 1868 by the Swedish 
